The idea was in vogue mid-decade until the emergence of ethereum, which was designed specifically for such use cases, and became the go-to launching pad for initial coin offerings, security tokens, non-fungible collectibles and the like. But Liquid, launched in September 2018, has started to make inroads; last week, BTSE announced it was integrating Blockstream’s Liquid versions of bitcoin and the dollar-pegged token USDT.